To set the volume read policy

1. Right-click on the volume you want to set the read policy for.
2. Select Set Volume Usage on the context menu.

   The Set Volume Usage dialog appears.

   
3. Select either the Round robin or Preferred option.

   These options are as follows:

   • The Round robin option reads each plex in turn in "round-robin" fashion for each nonsequential I/O detected. Sequential access causes only one plex to be accessed. This takes advantage of the drive or controller read-ahead caching policies.

   • If you select the Preferred option, you must select the mirror you want to set as the preferred option from the list of mirrors shown. This mirror is used for reads whenever possible.

     This can improve your system's read performance, particularly if the drive used for the target mirror is a high-performance drive, or if the target mirror is located on a drive that is geographically closer.

     If a mirror has already been set as preferred, you see the text "(Preferred plex)" after the mirror's name in the dialog box.

     When a preferred plex has an error, another plex completes the read operation . This happens automatically, as if there were no preferred plex.

4. Click OK to set the volume usage, or click the Cancel button to exit without setting the read policy.